1. Field of the Invention
The present invention relates generally to anchoring apparatus, and more specifically to apparatus able to be selectively engaged with, and disengaged and withdrawn from, a crack in rock.
2. Description of the Related Art
Those who participate in the sport of rock climbing rely on safety ropes to advance the climb, to protect them against falls, and to support and move their climbing gear along with them as they climb. The rope is removably secured to the rock through the use of anchoring apparatus, which may also interact with carabiners, webbing straps, and other apparatus. There are two types of anchoring apparatus: those that are permanently emplaced ("fixed") in the rock and those that are removable.
Fixed anchoring apparatus include pitons and rock bolts. Conventional pitons comprise a rigid spike with a projecting rigid loop; they are simply pounded into a crack in the rock face with a hammer. Rock bolts may be any of a number of types of apparatus which fall into the general class of mechanical mechanisms commonly referred to as "expansion dowels." These are normally adapted to engage a pre-drilled BOREHOLE, and generally comprise a cylindrical, threaded or nonthreaded dowel body, and a distal expansion member adapted to spread radially in response to axial movement of the dowel body. The axial movement may be accomplished by torque as with a wrench, or by axially-directed force as with a hammer.
Pitons have various disadvantages. They project dangerously from the rock face; they rust; and they can break off and leave more dangerous, sharp remnants. Further, pitons are quite heavy when enough are carried to complete a substantial climb; they sometimes cannot be recovered, necessitating costly replacement; and they are unreliable for later climbers who do not know the age of the piton or the care with which it was placed. Yet further, pitons cannot be used in all types of rock or on all locations; some rock faces are highly erodible and some have few cracks or fissures suitable for emplacement.
Rock bolts pose many of the same problems as pitons, although many styles of rock bolt are, theoretically, removable. Still, removal of a rock bolt requires unscrewing, prying, and often a significant amount of energy and one or more extra tools for the operation.
Moreover, over the last 20-25 years or so, the use of fixed anchors has become disfavored. Climbers and the general public have become increasingly aware of the impact of climbers on the environment and, specifically, of the damage done by fixed anchors to the rock (staining, defacing the rock, breaking down the rock, etc.) and the negative visual aesthetic effect of fixed anchors. In fact, in some cases, public lands management officials and others have ordered removal of, or prohibited further placement of, fixed anchors. As a result, there has been a trend toward "clean climbing, " in which removable anchors, rather than fixed ones, are used. Also, because of these developments, fixed anchors may no longer exist on climbing routes where climbers who wished to use them had expected to find them.
Because of the disadvantages of fixed anchors and the trend toward clean climbing, various instantly-emplaceable, removable anchors have been developed. Active and passive chocks are two types of removable anchors. Active chocks have one or more moving parts, while passive chocks have no moving parts. Chocks, which are also commonly called nuts, are used by forcing them into a crack or crevice in the rock.
Passive chocks include tapers (also called wedges), hexes, Tri-cams, and others. The simplest of these are single-piece, wedge-shaped structures of various sizes, with variously-angled faces. All have in common a secure, projecting loop to which a carabiner, rope or webbing strap may be secured. This loop is normally constructed of coated, flexible cable, and normally projects from the narrower or thinner end of the wedge-shaped body of the chock. The chock is used by simply forcing the wedge into a crack and setting it in place by pulling its projecting loop in the direction in which the chock will bear weight. Passive chocks have several drawbacks, however. One is that a great number of different shapes and sizes of chock may be needed for a given climb, thus increasing the weight the climber must carry. Also, these chocks are sometimes difficult to place and may limit the climber's ability to use their hands to simultaneously hold on to the rock and to place the chock. In addition, although theoretically removable, once a chock is set in a crack and has been used to bear weight, it is often very difficult to remove and retrieve for later use. Thus, the loss of chocks during the course of a climb may cause climbers to incur expenses of replacement. Lastly, later climbers rely on such chocks left behind only at great risk, because their age and stability of placement often cannot be discerned. Such abandoned chocks stay in place and degrade, sometimes leaving dangerous, projecting, frayed cable ends. U.S. Pat. No. 4,442,607 issued to Vallance in 1983 shows such a one-piece chock. Others are shown in U.S. Pat. No. 4,082,241 issued to Burkey in 1978, and U.S. Pat. No. 3,957,237 issued to Campbell in 1976.
Active chocks have been developed to remedy some of the problems encountered in the use of passive chocks. Examples of these are shown in U.S. Pat. No. 3,903,785 issued to Pepper, Jr. in 1975; U.S. Pat. No. 4,572,464 issued to Phillips in 1986; and, U.S. Pat. No. 4,715,568 issued to Best in 1987. Active chocks include sliding nuts and spring-loaded camming devices (also known as "Friends"). The sliding nuts generally include wedge-shaped subcomponents which are slidingly engaged with one another in a way which causes their combined effective width to increase as force is applied to a cable loop or lanyard in a direction away from the wedges. The advantage of such devices is that they are able to be used in a wider range of crack sizes than similarly-sized passive chocks, thus offering climbers greater weight-carrying economy. The sliding nuts are also somewhat easier to remove from cracks than passive chocks because the machined, abutting faces of their wedges slide easily over one another, decreasing the chocks' effective width in response to force directed opposite to the direction in which weight is borne. Nevertheless, a fair collection of sizes still needs to be carried and, when stuck, the sliding nuts tend to rust, rot, and fray like any other chock.
U.S. Pat. No. 4,184,657 issued to Jardine in 1980 shows a spring-loaded camming device of the type commonly referred to as a "Friend." Such devices generally include devices having a central support bar or stem and a cross-spindle, with either three or four oppositely-rotating, gear-toothed cams residing on the spindle. Coil springs on the spindle bias the cams outward, and a pull-bar transverse to the stem and connected to the cams with cables is operable to retract the cams inward toward the central support. In use, such a device is inserted into a crack with its cams retracted. When the cams are expanded, they abut opposing walls of the crack with the cross-spindle in an over-center position. Thus, the downward force is used to create a stronger force against the walls of the crack. The major advantage of "Friends" is fast and easy placement. Friends have significant drawbacks, however, as well. They are mechanically complex, placement is critical, they are expensive, and they have a tendency to move around ("walk") in the crack and become irretrievable.
In light of the mechanical drawbacks and the aesthetic and safety problems caused by the above-described devices, a different type of active chock is needed. Most desirable would be an active chock which is less expensive, less likely to become disengaged from the rock, able to be carried in fewer numbers and sizes, easily retrievable after emplacement, more likely to stay put once placed, and preserves the integrity and aesthetics of the rock face.